I was just wondering if anyone has replaced the steel screws that secure drivers to the speaker cabinet with brass screws as sugested in the virtual dynamics video. They said the steel screws ring and that brass screws make quite an improvement in sound.

Yes, I did and it made a noticeable difference for the better. As I understand it, the steel screws can affect the magnetic field of the tweeter, where the brass screws do not. Whatever it is, it cleans up the highs.